Carts are used to transport items in commercial establishments, such as groceries in supermarkets and luggage in airports. Customers place their items into such carts in order to transport the items to their parked vehicle or other destinations. When customers are done with the carts, the carts are placed in central collection areas or simply left unattended. Often the central collection areas serve as rental and return stations such that the customer is reimbursed for returning a cart.
Unattended carts pose problems. Many existing carts do not have brakes. These unrestrained carts can roll freely and cause damage to both persons and property. This is of particular concern on train platforms, where an unrestrained cart can cause damage to the transportation system. The carts themselves also sustain damage thereby reducing the useful life of the cart. Therefore a brake system is needed that automatically engages when the cart is left unattended in certain installations.
Several attempts have been made to employ brakes in cart. Most existing cart brakes are attached to the cart frame and operate on the outside of the tire tread. A brake shoe presses against the tire tread to slow down the cart. This has several disadvantages. Furthermore, the rental and return mechanisms that identify the cart and capture and release the cart require a very consistent wheel diameter. If the wheels wear more than 0.10 inches, the mechanisms will not work reliably. The tire tread is abnormally worn down, reducing the traction and ultimate safety of the cart. As the tread wears, brake performance is diminished. In addition, the wheels must be replaced at regular intervals which increases the overall cost of maintaining carts. Also, brake mechanisms acting on the outside of the wheel are more susceptible to damage. For example, the brakes can be easily struck by a foreign object such as a foot or other carts. Also, the tire tread tends to pick up debris, water and other contaminants which damage and reduce the overall effectiveness of the braking mechanism. Therefore a need exists for a durable brake which will not degrade the tire nor reduce the operational safety of the cart.
Nestable carts place certain demands on the braking system. First, the braking system must be compatible with the typical rental-return station. A common type of rental-return station accepts the rear wheel of a cart through a guided wheel slot. The wheel fits snugly within the slot and the slot opening is locked to prevent unauthorized access. The slot retains the cart for the next paying customer. A brake on the outside of the wheel will not easily fit within the guided wheel slot. Furthermore, the rental and return mechanisms that identify the cart and capture and release the cart require a very consistent wheel diameter. If the wheels wear more than 0.100", the mechanisms will not work reliably. Even if the brake fits within the slot, it is highly susceptible to damage by the guided wheel slot. Therefore it is advantageous for the brake to located within the wheel.
Another requirement of nestable carts is the release of the braking mechanism. Carts are often nested together and returned to the central collection area in a long string of carts. When the carts are nested, all brakes must be released. Therefore, the brakes of the front cart must disengage when nested with another cart.
Therefore, a need exists for a durable cart brake mechanism that will automatically engage when left unattended. The brake must be compact enough to fit within a wheel and corresponding wheel track and the brake must disengage when nested with another cart to facilitate en masse cart movement.